A lock plate for use as a guard for a latch bolt of a spring lock. The lock plate has a flat face portion with a curved first end and an L-shaped second end including a curved outwardly and forwardly extending arm. A recess is formed in the flat face portion from which a tongue extends. The lock plate is configured to nest on a striker plate of a spring lock for attachment with same screws by which the striker plate is attached to a door jamb. The outwardly and forwardly extending arm and the tongue blocking access to the latch bolt by a foreign object such as a credit card.